An internal combustion engine requires oxygen for the fuel utilized by the engine to be effectively combusted. Oxygen is typically supplied to such engines by drawing ambient air from the external environment into the engine. While the air drawn into the engine provides the necessary oxygen, ambient air also contains a large quantity of nitrogen. The high temperatures generated by internal combustion engines cause this nitrogen to react with any unused oxygen and results in the formation of nitrogen oxides [NOX], which are considered to be one of the main environmental pollutants emitted by vehicle engines.
Exhaust gas recirculation (EGR) was developed as a means for reducing NOX emissions by recycling a portion of the exhaust gases generated by a vehicle's engine back into the air intake of the engine. Exhaust gases contain much less oxygen than ambient air and by mixing the exhaust gases with fresh air drawn into the engine, the overall oxygen consumption of the engine is reduced. Providing the engine with less oxygen decreases the combustion temperature and, consequently, reduces the amount of pollutants emitted by the vehicle.
The inclusion of turbochargers in the engine systems of vehicles such as diesel cars and trucks is commonplace. More recently developed turbochargers include bearings that do not require external lubrication i.e., oil. Such bearings typically include a polymeric surface coating that can be damaged or degraded by physical contact with oil or other hydrocarbons. Degradation of this polymeric surface decreases the performance and effectiveness of such bearings and can reduce the overall performance and longevity of the turbocharger.
Oil in the form of an aerosol and/or vapor, as well as solid particulate matter, is often found in the exhaust gases generated by internal combustion engines. Thus, in vehicles that utilize both exhaust gas recirculation systems and turbochargers with oil-free bearings, the possibility exists that certain contaminants present in the re-circulated exhaust gases can damage the turbocharger's bearings. Therefore, the need exists for a filtration device that will safely and effectively remove oil aerosols and other contaminants from exhaust gases re-circulated to a turbocharger that is included as part of a vehicle's engine system.